The document discusses different types of defibrillators used to treat cardiac arrest. It describes a standard defibrillator that sends electrical shocks to the heart to treat ventricular fibrillation and tachycardia. An implantable cardioverter-defibrillator (ICD) monitors heart rhythm and delivers shocks to terminate ventricular tachycardia and fibrillation. An automated external defibrillator is a portable device that can diagnose and treat ventricular fibrillation and tachycardia through defibrillation, and is designed to be used by laypeople to provide emergency treatment.